Apparatus and method for logical operation utilizing joint measurement

Abstract

Disclosed is a method for a logical operation performed by a quantum computing device, which may include: placing a data patch in which information is stored and computed, and a first ancilla patch which is consumed during a logical operation at a predetermined first interval; placing a first logical ancilla qubit between the data patch and the first ancilla patch; placing a second logical ancilla qubit to have a predetermined distance from one side of the first ancilla patch; and performing a joint measurement utilizing the data patch and the first ancilla patch.

What is claimed is: 
     
         1 . A method for a logical operation performed by a quantum computing device, the method comprising:
 placing a data patch in which information is stored and computed, and a first ancilla patch which is consumed during a logical operation at a predetermined first interval;   placing a first logical ancilla qubit between the data patch and the first ancilla patch;   placing a second logical ancilla qubit to have a predetermined distance from one side of the first ancilla patch; and   performing a joint measurement utilizing the data patch and the first ancilla patch.   
     
     
         2 . The method of  claim 1 , wherein the data patch corresponds to a first logical qubit in which a first physical qubit is encoded with a surface code, and
 the first ancilla patch corresponds to a second logical qubit in which a second physical qubit is encoded with the surface code.   
     
     
         3 . The method of  claim 2 , wherein each of the first logical qubit and the second logical qubit includes
 a data qubit storing logical information,   an X stabilizer formed at one side of the data qubit, and   a Z stabilizer formed at one side of the data qubit.   
     
     
         4 . The method of  claim 3 , wherein each of the X stabilizer and the Z stabilizer includes a measurement qubit. 
     
     
         5 . The method of  claim 1 , wherein the performing of the joint measurement utilizing the data patch and the first ancilla patch includes
 performing a logical S operation in the data patch by performing a joint ZY measurement in the data patch and the first ancilla patch.   
     
     
         6 . The method of  claim 5 , wherein the performing of the logical S operation in the data patch includes
 initializing the first ancilla patch to a 0 state,   initializing the first logical ancilla qubit to a + state,   initializing the second logical ancilla qubit to the 0 state, and   performing a joint ZY measurement in the data patch and the first ancilla patch by using a stabilizer between the data patch and the first ancilla patch.   
     
     
         7 . The method of  claim 1 , wherein the performing of the joint measurement utilizing the data patch and the first ancilla patch includes
 performing a logical SH operation in the data patch by performing a joint XY measurement in the data patch and the first ancilla patch.   
     
     
         8 . The method of  claim 7 , wherein the performing of the logical SH operation in the data patch includes
 initializing the first ancilla patch to the 0 state,   initializing the second logical ancilla qubit to the 0 state, and   performing a joint XY measurement in the data patch and the first ancilla patch utilizing a stabilizer between the data patch and the first ancilla patch.   
     
     
         9 . The method of  claim 1 , wherein the performing of the joint measurement utilizing the data patch and the first ancilla patch includes
 placing a second ancilla patch at a location which is not duplicated with the first ancilla patch at a predetermined second interval from the data patch,   placing a third logical ancilla qubit between the data patch and the second ancilla patch, and   performing a logical T operation in the data patch by performing a joint ZZ and ZY measurement in the data patch, the first ancilla patch, and the second ancilla patch.   
     
     
         10 . The method of  claim 9 , wherein the performing of the logical T operation in the data patch includes
 initializing the first ancilla patch to the 0 state,   preparing the second ancilla patch in a predetermined magic state,   initializing the first logical ancilla qubit and the third logical ancilla qubit to the + state,   initializing the second logical ancilla qubit to the 0 state, and   performing the joint ZZ & ZY measurement to the data patch, the first ancilla patch, and the second ancilla patch by using a stabilizer between the data patch and the first ancilla patch and a stabilizer between the data patch and the second ancilla patch.   
     
     
         11 . A non-transitory computer-readable medium including a computer program, wherein the computer program allows a quantum computing device to perform a method for a logical operation, the method comprising:
 placing a data patch in which information is stored and computed, and a first ancilla patch which is consumed during a logical operation at a predetermined first interval;   placing a first logical ancilla qubit between the data patch and the first ancilla patch;   placing a second logical ancilla qubit to have a predetermined distance from one side of the first ancilla patch; and   performing a joint measurement utilizing the data patch and the first ancilla patch.   
     
     
         12 . A quantum computing device for a logical operation, comprising:
 a processor; and   a memory,   wherein the processor performs   an operation of placing a data patch in which information is stored and computed, and a first ancilla patch which is consumed during a logical operation at a predetermined first interval,   an operation of placing a first logical ancilla qubit between the data patch and the first ancilla patch,   an operation of placing a second logical ancilla qubit to have a predetermined distance from one side of the first ancilla patch, and   an operation of performing a joint measurement utilizing the data patch and the first ancilla patch.